Getting all of your infants milestones is hard work!

My sim had twins, hard work getting all the milestones before they age up. I hadn't gotten all of them and all of a sudden (after visiting another lot) my twins are back to square 1. They cant even sit in a highchair or learn to crawl anymore. Two days until age up!

Also, is anyone else getting annoyed at how the parents keep putting the infants in the crib or just doing what they like rather than follow the instructions given? I'm getting so frustrated!